20
6; 11; 9; 14; 12; 17; 15; 20; 18 there are 2 series in one with the increment of 3: 6-9-12-15-18 11-14-17-20
20... as once you add 5 to the prev number and then sub 2
20 is the answer. The pattern is +5, -2.
What number should replace the question mark?
12 - - - 25
5 - - - 11
21 - - - 43
18 - - - 37
2 - - - ?
28 -> 9
52 -> 15
84 -> 23
20 -> 7
100 -> ?